Case Report: Repeated Intralesional Injections of Autologous Mesenchymal Stem Cells Combined With Platelet-Rich Plasma for Superficial Digital Flexor Tendon Healing in a Show Jumping Horse

Abstract

In the present case report a show jumping 10-year-old Sella Italiano gelding, presented with severe lameness, swelling and pain at palpation of the mid-metacarpal region of the left forelimb. Clinical and ultrasound examination diagnosed a chronic tendonitis of the central region of the superficial digital flexor tendon (SDFT). The lesion was a reoccurrence since it developed from a previously healed injury. The horse had to stop competing and was unresponsive to gold-standard treatments as Non-steroidal anti-inflammatory drugs (NSAIDs) and conservative management after 6 months of therapy. The animal was subjected to repeated intralesional injections of autologous adipose-derived mesenchymal stem cells (AD-MSCs) combined with autologous platelet-rich plasma (PRP). The combined treatment was administered twice in a 1-month interval. The healing process was assessed through clinical examination, ultrasound imaging and quantification of oxidative stress products and inflammatory mediators in blood plasma. After 2 weeks from first injection, a reduction of concentration of oxidative-derived products was observed, together with an increase of anti-inflammatory cytokines and pro-mitotic growth factors. These results were reflected clinically as the horse showed a reduction of lameness along with swelling and pain after 4 weeks. At the 1-year follow-up, the horse showed no signs of lameness and swelling. The ultrasonographic examination highlighted a compact fiber alignment with a normal echogenic tendon as observed in the sound contralateral limb. Moreover, the horse went back to the previous level of competition. Our results suggest the positive effects of a repeated intralesional injection of AD-MSCs and PRP for the treatment of a chronic tendonitis with long-term effects and an improvement for both equine quality of life and athletic performance.

Keywords: SDFT; equine orthopedics; horse; mesenchymal stem cells; platelet-rich plasma; regenerative medicine; tissue regeneration.

Figure 1

Schematic timeline of the clinical case reporting clinical examinations, ultrasonographic evaluations and therapy protocol.

Figure 2

Transversal and longitudinal images of the central area of the superficial digital flexor tendon in the mid-metacarpal region performed at day 0 (T0, day of therapy injection), T1 (4 weeks), and T2 (52 weeks). At T0 the SDFT is characterized by a hypoechoic area (c) along with an abnormal fiber alignment (d). After 4 weeks (T1), the same area resulted less hypoechoic (e) and the fiber pattern was more aligned (f) while at T2 the area showed a normal echogenicity (g) and fiber disposition (h) as in the sound contralateral limb (a,b). White circle, corresponding injury area in transverse images; black arrow-head, injury area in longitudinal images.